RU1800383C - Device for measuring phase shift - Google Patents

Abstract

Used: in measurement technology to measure the phase shift between currents or voltages. SUMMARY OF THE INVENTION: A device for measuring a phase shift comprises a tape measure suspended on opposing springs, which are subjected to electromagnetic forces of equal magnitude and oppositely directed. Traction forces are created by two inductors, in the grooves of which three-phase windings are laid. Measuring windings are placed at the ends of the inductors, the magnitude of the movement of the tape core is proportional to the phase difference between the currents in the measuring windings. The absence of friction and low energy consumption from the measuring circuit allow increasing the accuracy of the measurement while maintaining high speed. 3 ill.

Description

The invention relates to measurement techniques, in particular to electrical measurements, and can be used to measure the phase shift between currents and. voltage

The purpose of the invention is to increase measurement accuracy.

The goal is achieved by the fact that in the device on opposing springs the tape measure is suspended in the air gap of two identical inductors, which are open magnetic circuits, in the grooves of which are laid three-phase windings that are connected in parallel and so that the magnetic fields of the inductors create equal, but electromagnetic pulling forces directed in opposite directions, and measuring windings are placed in the extreme grooves, which are connected in pairs in series.

Fig. 1 is a diagram of an inventive device for measuring phase shift; on the

Fig. 2 - graphs of experimental dependences of electromagnetic pulling forces of inductors; in Fig.Z - calibration dependence of the proposed device.

The device for measuring the phase shift contains a tape measure 1 connected to the reading device, counter springs 2 and 3, inductors 4 and 5 with three-phase windings A, B, C connected to terminals 6, 7, 8, measuring (end) windings 9, 10 and 11, 12, connected respectively to the terminals 13, 14 and 15, 16. When a three-phase voltage is applied to the terminals 6, 7, 8, the magnetic fields of the inductors 4, 5 create equal but opposite electromagnetic pulling forces FI and F2, which are attached to the tape core 1.

The pulling forces of the inductors 4 or 5 are proportionally related to the phase p of the current in the end measuring winding, measured (L

WITH

00

oh oh

with

00

with

relative to the phase of the rv current in the middle winding B (see figure 2, dependencies 17, 18):

F F0 + K OB - #)

where K is the coefficient.

If the windings of the inductors are connected to a star and both middle windings B are included in the middle phase of the supply voltage (terminal 7), then the phases of the currents flowing through these windings coincide, i.e.

 (PB2 PB

Hence, the pulling forces generated by each inductor are determined by the following expressions:

Fi FO + K (pv-pm) F2 Fo + K (pv-pk2)

where (pk and p & are the phases of the currents flowing respectively in the terminal windings 9,10 and 11,12,

The total pulling force F, moving the core 1, is equal to the difference of the electromagnetic pulling forces of the inductors:

FX F2 - Fi

Substituting expressions (2) and (3) into equation (4), we obtain

FЈ K () K

Under static equilibrium

C X FЈ

where C is the total stiffness of the opposing springs 2, 3;

x-shift core 1, The calibration dependence (3) of the device for measuring the phase shift is determined by the expression

x fps (pki) fps

Thus, the phase difference between the currents in the measuring windings is proportional to the movement of the tape core 1.

In the inventive device, there is practically no friction, since the tape measure, making translational motion, is suspended in the air gap of the inductors with the help of opposing springs.

1

twenty

25

thirty

35

40

5 50

-

High speed is determined not only by the execution of a suspended element in the form of a light tape core, but also by the speed of a traveling electromagnetic field created by the excitation current of three-phase windings of inductors:

V 2 t fch,

where t is the pole division;

fi is the frequency.

By choosing a certain value of the pole division, it is possible to ensure the corresponding speed and the required speed. The pulling force in the claimed device is created due to the magnetic field energy of three-phase windings. The energy of the measuring windings is spent only on the redistribution of the pulling forces of the inductors and, compared with the energy consumption for overcoming the opposing force of the springs, is small and, therefore, the energy consumption from the measuring circuit is small. All this allows us to generally increase the accuracy of the measurement when using the proposed device. Studies of the proposed device for measuring the phase shift showed that its basic error does not exceed 1%. In Fig. 3, a calibration dependence 19 is shown, constructed from experimental data.

Thus, as shown by theoretical and experimental studies, the proposed device compares favorably with the known ones, since it has high speed, lack of friction and low energy consumption from the measuring circuit, i.e. allows to increase measurement accuracy.

claims

A device for measuring the phase shift comprising non-magnetic measurment, two magnet wires, measuring windings and an excitation winding. Characterized in that, in order to increase the measurement accuracy, the measurment is made in the form of a tape and horizontally mounted on opposing springs in the air gap of two identical inductors , which contain open magnetic circuits with grooves, in the internal grooves of which are laid three-phase windings connected together, in parallel, and in the extreme grooves are laid measuring windings, connected by paired in series, with the magnetic field of the inductors creating equal and oppositely directed pulling forces.

-F

Pi / e.2

FIG. f

fe-fle

t

d

Fig.Z